boosting exp rates is not exaclty the best option to me but i guess it can be done as an easy and quick way to temporaly ease the pain of low/mid players till something else is implemented.
if you know where and how to leveling you can get lv.80 soloing in 3 -4 days max. But I agree many of the new players or not so experienced on it, will take a month to get lvl 70 at least.. or will quit trying, so much boredoom. But I think GM did explained that leveling will be possible also tru questing or by another alt system on the next updates..
Increasing experience rates is only temporarily efficient. In the long run, GMs need to focus on attracting new players, which involve advertising, better support to players, new low level features, and much much more.